The present disclosure relates to a gas-powered fixing tool, such as a nail gun for example, and to the method of operation of same.
The present disclosure relates to anchoring or fixing tools, said to be gas-powered, which means to say tools comprising an internal combustion engine which works by igniting an air-fuel mixture inside a combustion chamber, the fuel being injected into the chamber by an injection device from a fuel receptacle referred to as a gas cartridge. Such tools are intended to drive fixing elements into supporting materials so that components can be fixed thereto. Gas-powered nail guns are very commonplace these days. As examples of fuels for the internal combustion engine, mention may be made of gasoline, alcohol, in liquid and/or gas form.
In general, such a tool is portable and comprises a casing in which the internal combustion engine that propels a piston that drives a fixing element is mounted. Such a tool may also comprise an electric battery as well as a holding, handling and firing handgrip on which a trigger by means of which the tool is actuated is mounted.
A firing cycle comprises several steps such as the distribution of a quantity of fuel by the cartridge, the admission of the fuel into the chamber, the mixing of the fuel with air in the chamber, the ignition and combustion of the mixture in order to drive the piston, and the evacuation of the combustion gases from the chamber.
The fixing tools equipped with two combustion chambers, namely a precombustion chamber and a combustion chamber are known. This type of tool in practice comprises three chambers because the tool comprises a third chamber, which will be referred to as a working chamber, in which a piston is slidably mounted for driving fixing elements. The combustion of the air-fuel mixture is intended to be initiated in the precombustion chamber, prior to the injection of this mixture into the combustion chamber in order to complete the combustion of the mixture. The precombustion and combustion chambers are separated from one another by a flap which is movable or deformable from a position in which it ensures fluidic communication between the precombustion and combustion chambers, and a position in which it isolates these chambers from each other, preferably hermetically. The tool in general also comprises gas intake and evacuation valves.
In the current art, the firing cycle or method of operation of a tool of this type comprises the following steps:                a) ignition of the gas in the precombustion chamber, causing an increase in pressure in the precombustion chamber,        b) displacement or deformation of said flap because of the increase in pressure in the precombustion chamber above a certain threshold, and passage of the gas into the combustion chamber,        c) combustion of said gas in the combustion chamber, causing an increase in pressure in the combustion chamber,        d) displacement of said piston from a rest position to a working position because of the increase in pressure in the combustion chamber,        e) reverse displacement of said piston from the working position because of a reduced pressure in the combustion chamber, and        f) evacuation of combusted gas from the precombustion chamber and/or the combustion chamber via said valve.        
The present disclosure proposes an improvement to this technology notably making it possible to shorten the duration of a firing cycle.